What’s Up DACT? Assuring Communications During Residential Fires

January 31, 2005 SSI Staff

Fire continues to take its toll in the residential sector. According to the United States Fire Administration (USFA) in Emmitsburg, Md., of all the fires that took place in the U.S. during 2001, 73 percent took place in one- and two-family homes. Of the total U.S. fires, the residential sector accounted for 78 percent of fire deaths, 67 percent of fire injuries and 76 percent of fire loss dollars.

The USFA statistical data also shows there are less fire alarm systems installed in one- and two-family homes than there are in apartments. This may be because apartment smoke alarms are often provided by landlords and are more often required by law.

In any case, one of the most important aspects of residential fire system installations in making sure smoke and fire is properly picked up and transmitted to the monitoring center. That means ensuring cabling used to send those signals is impervious or protected from fire, heat or other potentially damaging elements.

Why No Central Station Response?
The following case study illustrates what can happen if fire system cable is not properly run.

In the beginning of 1998, a single-family home was severely damaged by fire that ravaged through the attic in quick order. According to the homeowner, it began when a plumber, working on a new swimming pool, caught the materials inside a wall on fire while soldering a copper pipe.

“He apparently ignited the paper between the siding and a stud adjacent to the pipe. On the other side of the stud was a 5-inch channel between the next stud that had no insulation whatsoever,” says the homeowner. “The fire migrated across the stud into the channel, which basically acted as a chimney, taking the fire up into the attic. Within minutes, fire was sweeping through the attic.”

The short and sweet of this situation is that there was a combination burglar/fire alarm system in the home, which did make an attempt to dial out to the central station. The wife, who was on the phone at the time, was disconnected when the panel’s digital alarm communicator transmitter (DACT) took action. However, later analysis revealed that the digital signal never made it to the central station. The question is why?

“Fortunately, we were home at the time. The plumber banged on the door and told us to call the fire department. My wife dialed 911 and reported the fire. There was no smoke inside [the house] at the time, so I have to assume that the alarm was tripped by the attic heat detectors melting down,” the homeowner adds.

While other cables were properly shielded, the telephone line was installed beneath the blanket-type insulation in the attic area. It was exposed on the underside of the rafters just beneath the roof.

Needless to say, while the other cables survived — long enough to trip the alarm system, the telephone line did not. Hence, there was no central station response and the homeowner has asked what he might do while rebuilding his home to avoid this situation in the future.

Going Above and Beyond Code
A preliminary analysis of the situation might suggest that the original installer of the phone line failed to do his or her job correctly. Those who install fire alarm systems in commercial settings, for example, shudder when they consider the use of a single phone line, but NFPA 72, Section 11.7.8.1, 2002 Edition, clearly calls for a single telephone line in residential settings. What’s more, there is no specific provision in NFPA 72 that requires the phone line be specifically protected in some manner.

A closer look reveals there are established standards concerning the specification of the cables an installer can use, whether it is in a home or large commercial structure. For example, in Article 800.49, it states, “Communications wires and cables installed as wiring within a building shall be listed as being resistant to the spread of fire in accordance with 800.50 and 800.51.”

Because this stipulation is found in the National Electrical Code (NEC), the installer would be unlikely to install a cable that was not resistive to the spread of fire. And, because the attic is not involved in return air, as is the case in many commercial facilities, the installer was not required to use plenum cable.

Survivability Issue in Residential
The issue of survivability usually pertains to the continued operation of notification appliance circuits (NACs) during a fire situation in structures where partial evacuation and relocation is a valuable tool in saving lives.

For this reason, most of the time, dealers are not concerned with this aspect of their fire alarm wires. However, in the case of the home fire cited above, perhaps survivability should have been on the mind of whoever ran the telephone line that failed in the attic. In NFPA 72, Section 3.8.4.1.1.4, it calls for protection for a NAC circuit when that circuit travels through an area to which it is not assigned (see “Fire Side Chat” in September 2002 issue).

“Notification appliance circuits and any other circuits necessary for the operation of the notification appliance circuits shall be protected from the point at which they exist the control unit until the point that they enter the notification zone that they serve …”

Although this section has absolutely nothing to do with a telephone line in a residential structure, perhaps security dealers should consider the general idea presented in this section and consider it as good advice when installing either telephone feed lines or the main cable that stretches from the alarm panel’s DACT to the point of demarcation.

Physical Protection Goes Long Way
Without a doubt, the physical protection of the main telephone line is important — not only to the protection of personal assets within a home — but also to the lives of those who live and visit there. Perhaps installers should offer an alternative to all prospective homeowner clients that include additional protection for this most crucial part of the life-safety chain.

There are several ways to do this, one being the use of type CMP communication cable, which is plenum. Another option is to use a piece of conduit from panel to demarcation, but it must be installed concurrent between these two positions.

Also, consider installing all your wires in an attic beneath the insulation so a raging fire will not so readily damage them. In addition, be sure to install fire stopping in all holes that you make, as well as knockouts in boxes and holes behind (see this month’s “Tech Talk”).

Another option is to install a combination burglar and fire alarm panel that carries a UL Listing for commercial fire. This would assure your panel contains two separate telephone lines, or perhaps one telephone line and some other means of signal backup, such as cellular.

When using two phone lines, it might be prudent if the installer runs each telephone feed line by a separate physical route.

Regardless how you choose to do it, a little extra care when installing the main telephone line will help assure a call for help reaches the central station by way of the DACT. Be sure to offer your future clients an alternative to the plain-old installation that so many of us have grown used to doing.

By educating your clients of the dangers, you not only will be doing them an invaluable favor, but you stand to make additional money providing that extra layer of protection that just might save a life.

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